Continental Drift

The shape of the geosphere is constantly changing. Erosion of beaches and landscapes occurs on a small level. Volcanoes can make larger changes all at once. But over millions of years the greatest change in the geosphere is due to continental drift.

The surface of the Earth and the crust beneath it float on a sea of molten lava called the mantle. Major cracks in the Earth, called faults, let some parts of the crust sink down into the mantle while others rise up out of it. Eventually this causes the continents to glide and shift their positions. The continents are moving about four inches a year, but over millions of years this adds up.

Thought Questions

• Which continents were next to each other in the past?
• When were the continents closest together?
• Was the Atlantic Ocean smaller, larger, or the same 130 million years ago?
• Do you think it will be cold or warm in Antarctica 250 million years from now?